Cement composition, self-leveling material or repair material

Abstract

To provide a cement composition comprising Portland cement and hemihydrate gypsum, which can form a mortar hardened body having excellent dimensional stability in water and has excellent rapid hardening properties.SOLUTION: There is provided a cement composition comprising a hydraulic component composed of Portland cement and hemihydrate gypsum, a limestone fine aggregate, a carbonate, a water-reducing agent, a thickening agent and a defoaming agent. Based on the total amount of the hydraulic component, the content of the Portland cement is 20 to 60 mass% and the content of the hemihydrate gypsum is 40 to 80 mass%. The content of the limestone fine aggregate is 50 to 250 pts.mass and the content of the carbonate is 0.30 to 1.8 pts.mass, the content of the water-reducing agent is 0.03 to 6.0 pts.mass, the content of the thickening agent is 0.03 to 4.0 and the content of the defoaming agent is 0.03 to 4.0 pts.mass, based on 100 pts.mass of the hydraulic component.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a cement composition and a self-leveling or repair material. [Background technology]

[0002] Generally, cement compositions are required to have excellent workability, sufficient compressive strength after hardening, and excellent dimensional stability. In particular, materials such as self-leveling materials and repair materials require excellent rapid hardening properties to shorten construction periods, and also require extremely good dimensional stability to prevent cracking and peeling from the adhesive surface after hardening.

[0003] Against this background, compositions containing Portland cement and gypsum hemihydrate have been the subject of much research, as they are expected to provide excellent rapid hardening properties and good dimensional stability in air due to the hemihydrate, as well as sufficient strength development due to the Portland cement.Patent Document 1 discloses a cement composition that contains Portland cement and gypsum hemihydrate as a material containing Portland cement and gypsum hemihydrate, and further contains a predetermined amount of inorganic fine powder, typified by calcium carbonate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-172801 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional cement compositions containing Portland cement and gypsum hemihydrate, dimensional stability, one of the important properties, has not been fully investigated, and there is still room for improvement. In addition to drying shrinkage, which is a common problem with general construction materials that use Portland cement, cement compositions containing Portland cement and gypsum hemihydrate are concerned about deterioration of dimensional stability under water immersion conditions (underwater dimensional stability), which is an issue specific to gypsum hemihydrate.

[0006] Therefore, a main object of the present invention is to provide a cement composition containing Portland cement and gypsum hemihydrate, which is capable of forming a hardened mortar having excellent underwater dimensional stability and also has excellent rapid hardening properties. [Means for solving the problem]

[0007] As a result of extensive research conducted by the present inventors to solve the above problems, they discovered that by using carbonate, a component that can act as a set retarder, and by adjusting the contents of each component in a cement composition containing a hydraulic component consisting of Portland cement and hemihydrate gypsum, limestone fine aggregate, carbonate, a water-reducing agent, a thickener, and an antifoaming agent within a predetermined range, the underwater dimensional stability of the hardened mortar body and the rapid hardening properties of the cement composition and a mortar material containing the same can be improved, and they have completed the present invention.

[0008] The present invention provides the cement compositions described in [1] to [3] and the self-leveling material or repair material described in [4]. [1] A cement composition comprising a hydraulic component consisting of Portland cement and hemihydrate gypsum, limestone fine aggregate, carbonate, a water-reducing agent, a thickener, and an antifoaming agent, The content of the Portland cement is 20 to 60 mass% and the content of the hemihydrate gypsum is 40 to 80 mass% based on the total amount of the hydraulic components, the content of the limestone fine aggregate is 50 to 250 parts by mass, the content of the carbonate is 0.30 to 1.8 parts by mass, the content of the water-reducing agent is 0.03 to 6.0 parts by mass, the content of the thickener is 0.03 to 4.0 parts by mass, and the content of the antifoaming agent is 0.03 to 4.0 parts by mass, relative to 100 parts by mass of the hydraulic component; Cement compositions. [2] The content of the hydraulic component is 15 to 70 mass% based on the total amount of the cement composition. [1] The cement composition according to [1]. [3] The carbonate is sodium bicarbonate. [1] or [2]. The cement composition according to [1] or [2]. [4] A cement composition according to any one of [1] to [3] and water, Self-leveling or repair material. [Effects of the Invention]

[0009] According to the present invention, there is provided a cement composition containing Portland cement and gypsum hemihydrate, which is capable of forming a hardened mortar having excellent underwater dimensional stability and also has excellent rapid hardening properties. Also, according to the present invention, there is provided a self-leveling material or repair material using such a cement composition. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

[0011] Unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. When a composition contains multiple substances corresponding to each component, the amount used or content of each component means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0012] [Cement composition] The cement composition of this embodiment contains a hydraulic component consisting of Portland cement and hemihydrate gypsum, limestone fine aggregate, carbonate, a water-reducing agent, a thickener, and an antifoaming agent. The cement composition of this embodiment is suitable for use in materials that require rapid hardening and dimensional stability, such as self-leveling materials used as underfloor materials in the construction of structural floors.

[0013] <Hydraulic component> Examples of Portland cement include ordinary Portland cement, high-early-strength Portland cement, ultra-high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, and sulfate-resistant Portland cement. Also, blended cements such as blast-furnace cement, fly ash cement, and silica cement can be used as a substitute for Portland cement. From the viewpoint of rapid hardening, the Portland cement is preferably high-early-strength Portland cement or ultra-high-early-strength Portland cement. From the viewpoint of dimensional stability in water, the Portland cement is preferably moderate-heat Portland cement or sulfate-resistant Portland cement.

[0014] The Blaine specific surface area of ​​Portland cement is preferably 3000 to 6000 cm 2 / g, more preferably 4000 to 5000 cm 2 / g, more preferably 4200 to 4800 cm 2 / g. The Blaine specific surface area of ​​Portland cement is a value measured in accordance with JIS R 5201:2015 "Physical Testing Methods for Cement." Portland cement with a specific surface area in this range tends to have improved fluidity and rapid hardening properties when combined with gypsum hemihydrate.

[0015] The content of Portland cement is 20 to 60 mass %, preferably 30 to 57 mass %, and more preferably 40 to 55 mass %, based on the total amount of hydraulic components. When the content of Portland cement is within this range, good fluidity and good rapid hardening properties tend to be more reliably obtained in addition to good underwater dimensional stability.

[0016] Examples of gypsum hemihydrate include α-gypsum hemihydrate, β-gypsum hemihydrate, and a mixture of α-gypsum hemihydrate and β-gypsum hemihydrate.

[0017] The Blaine specific surface area of ​​the hemihydrate gypsum is preferably 5000 to 12000 cm 2 / g, more preferably 6000 to 11000 cm 2 / g, more preferably 7000 to 10000 cm 2 / g. The Blaine specific surface area of ​​gypsum hemihydrate refers to a value measured in accordance with JIS R 5201:2015 "Physical Testing Methods for Cement." When the specific surface area of ​​gypsum hemihydrate is in this range, dimensional stability in water, high fluidity, and rapid hardening tend to be further improved when combined with Portland cement.

[0018] The content of gypsum hemihydrate is 40 to 80 mass%, preferably 43 to 70 mass%, and more preferably 45 to 60 mass%, based on the total amount of hydraulic components. When the content of gypsum hemihydrate is in this range, good fluidity and good rapid hardening properties tend to be more reliably obtained in addition to good underwater dimensional stability.

[0019] The content of the hydraulic component is 15 to 70 mass %, preferably 20 to 55 mass %, and more preferably 25 to 45 mass %, based on the total amount of the cement composition.

[0020] <Limestone fine aggregate> The limestone fine aggregate preferably has a maximum particle size of 0.850 mm or less, and the content of coarse particles with a particle size of more than 0.600 mm in the limestone fine aggregate is 5 mass % or less. The particle size of the limestone fine aggregate refers to a value measured in accordance with the sieving test method for aggregates specified in JIS A 1102:2014 "Sieving test method for aggregates." In addition, in this specification, "coarse particles with a particle size of more than 0.600 mm" refers to the mass fraction (%) of limestone fine aggregate that is retained on a sieve with 0.600 mm mesh.

[0021] The content of the limestone fine aggregate is 50 to 250 parts by mass, preferably 60 to 220 parts by mass, more preferably 70 to 200 parts by mass, and even more preferably 80 to 180 parts by mass, relative to 100 parts by mass of the hydraulic component. By keeping the content of the limestone fine aggregate within this range, good fluidity and good dimensional stability can be obtained.

[0022] <Carbonates> Carbonates are components that can act as setting retarders. Examples of carbonates include sodium bicarbonate (sodium hydrogen carbonate), sodium carbonate, and potassium carbonate. The carbonate is preferably sodium bicarbonate because it can provide good dimensional stability and fast curing properties.

[0023] The content of the carbonate is 0.30 to 1.8 parts by mass, preferably 0.40 to 1.6 parts by mass, more preferably 0.45 to 1.4 parts by mass, and even more preferably 0.50 to 1.3 parts by mass, relative to 100 parts by mass of the hydraulic component. By having the content of the carbonate in this range, good fluidity, good dimensional stability, and good fast curing properties can be obtained.

[0024] <Water reducing agent (superplasticizer)> Examples of the water-reducing agent (fluidizing agent) include commercially available water-reducing agents that also have a water-reducing effect, such as formaldehyde condensates of melamine sulfonic acid, casein, calcium caseinate, polycarboxylic acid compounds, polyether compounds, and polyether polycarboxylic acid compounds. The water-reducing agent is preferably a commercially available water-reducing agent such as a polyether compound or a polyether polycarboxylic acid compound.

[0025] The content of the water-reducing agent is 0.03 to 6.0 parts by mass, preferably 0.06 to 4.0 parts by mass, more preferably 0.09 to 3.0 parts by mass, and even more preferably 0.15 to 2.0 parts by mass, relative to 100 parts by mass of the hydraulic component. When the content of the water-reducing agent is within this range, good fluidity tends to be obtained.

[0026] <Thickener> Examples of the thickener include commercially available thickeners such as polysaccharide compounds, protein compounds, latex compounds, and water-soluble polymer compounds.

[0027] The viscosity (20°C) of a 2% by mass aqueous solution of the thickener is preferably 50 to 100,000 mPa·s, more preferably 100 to 80,000 mPa·s, even more preferably 200 to 30,000 mPa·s, and particularly preferably 300 to 3,000 mPa·s. The viscosity is a value measured at 20°C using a B-type viscometer on a 2% by mass aqueous solution of the thickener.

[0028] The content of the thickener is 0.03 to 4.0 parts by mass, preferably 0.06 to 3.0 parts by mass, more preferably 0.12 to 2.0 parts by mass, and even more preferably 0.15 to 1.5 parts by mass, relative to 100 parts by mass of the hydraulic component. When the content of the thickener is within this range, good material separation resistance tends to be obtained.

[0029] <Antifoaming agent> Examples of antifoaming agents include synthetic substances such as silicone compounds, alcohol compounds, fatty acid ester compounds, and polyether compounds, natural substances derived from plants, and mineral oils. From the viewpoint of cost and availability, the antifoaming agent is preferably a silicone compound, a fatty acid ester compound, or a polyether compound. Adding an antifoaming agent to a cement composition tends to provide a good surface condition and rapid hardening.

[0030] The content of the antifoaming agent is 0.03 to 4.0 parts by mass, preferably 0.06 to 3.0 parts by mass, more preferably 0.12 to 2.0 parts by mass, and even more preferably 0.15 to 1.5 parts by mass, relative to 100 parts by mass of the hydraulic component. When the content of the antifoaming agent is within this range, good surface condition and good rapid hardening properties tend to be obtained.

[0031] <Shrinkage reducing agent> The cement composition of this embodiment may further contain a shrinkage-reducing agent. Examples of shrinkage-reducing agents include lower and higher alcohol alkylene oxide adducts and glycol ether derivatives. The shrinkage-reducing agent is preferably a polyether derivative. Generally, the addition of silica fume or the like increases the amount of shrinkage due to drying in air, so adding a shrinkage-reducing agent to the cement composition tends to improve dimensional stability in air.

[0032] The content of the shrinkage reducing agent is preferably 0.05 to 10.0 parts by mass, more preferably 0.1 to 7.0 parts by mass, even more preferably 0.2 to 5.0 parts by mass, and particularly preferably 0.3 to 3.0 parts by mass, relative to 100 parts by mass of the hydraulic component. When the content of the shrinkage reducing agent is within this range, good dimensional stability tends to be obtained.

[0033] [Mortar material] The mortar material of this embodiment contains the above-mentioned cement composition and water. The mortar material of this embodiment can be manufactured (prepared) by mixing and kneading the above-mentioned cement composition with a predetermined amount of water. The mortar material of this embodiment has good fluidity, so that when applied to the floor surface of a structure, a horizontal and flat floor surface can be easily formed. A mortar material with workability can be obtained by appropriately changing the amount of water blended when preparing the mortar material. The mortar material of this embodiment can be suitably used as a self-leveling material or repair material.

[0034] Examples of water include tap water, distilled water, deionized water, etc. The amount of water to be added is preferably 20 to 30 parts by mass, more preferably 20 to 29 parts by mass, even more preferably 21 to 28 parts by mass, and particularly preferably 21 to 26 parts by mass, per 100 parts by mass of the cement composition.

[0035] [Hardened mortar] The hardened mortar of this embodiment can be obtained by hardening the above-mentioned mortar material. The hardened mortar has rapid hardening properties that allow light walking on the surface early, appropriate compressive strength, and underwater dimensional stability, and therefore can be used as a floor underlayment material (e.g., a self-leveling material) or repair material for structures in buildings such as schools, apartment buildings, convenience stores, and hospitals.

[0036] [evaluation] <Underwater dimensional stability> Underwater dimensional stability can be evaluated by measuring the dimensional change of a hardened mortar when immersed in water, in accordance with the length change measurement method described in JASS 15M-103 "Quality Standard for Self-Leveling Materials" of the Architectural Institute of Japan (General Incorporated Association). According to JIS A 1129-2:2010 "Contact Gauge Method," the length of the hardened mortar is measured immediately after removal from the formwork and after subsequent immersion in water for a specified age. The change in length during immersion relative to the length immediately after removal can be defined as the underwater dimensional change. From the perspective of underwater dimensional stability, the underwater dimensional change at 28 days is preferably in the range of -1200 μm / m (shrinkage) to 1200 μm / m (expansion). A material that satisfies this range of underwater dimensional change at 28 days can be evaluated as having excellent underwater dimensional stability.

[0037] <Fast curing> The Shore hardness of the hardened surface is an indicator of the rapid hardening of mortar. Shore hardness can be evaluated by measuring the surface of the hardened material using a spring hardness tester Type D (manufactured by Ueshima Seisakusho Co., Ltd.).

[0038] The Shore hardness of the hardened mortar material 2 hours (2h) after pouring (construction) of the mortar material is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more. When the Shore hardness is in this range, the mortar material can be evaluated as having excellent rapid hardening properties. [Example]

[0039] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0040] [Materials used] The materials used in the examples and comparative examples are shown below. (1) Hydraulic component (1-1) Portland cement Portland cement [PC] (high-early-strength Portland cement, manufactured by UBE Mitsubishi Cement Co., Ltd., Blaine specific surface area 3660 cm 2 / g) (1-2) Hemihydrate gypsum ·β Hemihydrate gypsum [HH] (Brain specific surface area 9040cm 2 / g) (2) Limestone fine aggregate Limestone fine aggregate [CC] (maximum particle size: over 0.425 mm and up to 0.600 mm, 0% by mass of coarse particles with particle sizes over 0.600 mm) (3) Sodium bicarbonate [J] (manufactured by Tosoh Corporation) (4) Sodium tartrate [S] (Fuso Chemical Co., Ltd.) (5) Sodium gluconate [G] (Tomita Pharmaceutical Co., Ltd.) (6) Sodium citrate [K] (manufactured by Iwata Chemical Co., Ltd.) (7) Sodium polyphosphate [P] (manufactured by Organo Corporation) (8) Sodium tripolyphosphate [TP] (manufactured by Taiyo Chemical Industry Co., Ltd.) (9) Water reducing agent [SP] (polycarboxylic acid compound) (10) Thickener [ST] (polysaccharide-based, viscosity of 2% by weight aqueous solution at 20°C: 1017 mPa·s) (11) Defoaming agent [DF] (polyether type)

[0041] [Preparation of cement composition] The above materials (total amount 10 kg) were mixed in the blending ratios shown in Table 1 to prepare cement compositions of Examples 1 and 2 and Comparative Examples 1 to 11. The materials were mixed for 5 minutes using an Eirich mixer.

[0042] [Table 1]

[0043] [Preparation of mortar material] The mortar materials of Examples 1 and 2 and Comparative Examples 1 to 11 were prepared by blending water with the cement compositions of Examples 1 and 2 and Comparative Examples 1 to 11. The mortar materials were prepared in a constant temperature and humidity chamber set at a room temperature of 5°C and a humidity of 65% RH. The amount of water blended in the mortar materials was 22 parts by mass per 100 parts by mass of the cement composition.

[0044] [Measurement of dimensional change in water] The underwater dimensional change was measured in accordance with the length change measurement method specified in JASS 15M-103, "Quality Standards for Self-Leveling Materials," published by the Architectural Institute of Japan (JASI). The dimensional change was measured when the hardened mortar was immersed in water. The length of the hardened mortar was measured immediately after removal from the formwork and after immersion in water for a specified age, in accordance with JIS A 1129-2:2010, "Contact Gauge Method." The change in length after immersion in water relative to the length immediately after removal was recorded as the underwater dimensional change. Measurements of the underwater dimensional change were performed in a constant temperature and humidity chamber set at a room temperature of 5°C and a humidity of 65%. The underwater dimensional change at 28 days is shown in Table 2.

[0045] [Shore hardness measurement] The mortar immediately after mixing was poured into a synthetic resin container with internal dimensions of 130 mm wide x 190 mm long x 17 mm high to a thickness of 10 mm. After 2 hours, the hardness (Shore hardness) of the hardened mortar surface was measured using a spring-type hardness tester Type D (manufactured by Ueshima Seisakusho Co., Ltd.). The results are shown in Table 2.

[0046] [Table 2]

[0047] The mortar of Comparative Example 2, which did not contain a component capable of acting as a set retarder, showed a large underwater dimensional change of the hardened mortar and significant expansion. The mortars of Comparative Examples 3 to 11, which contained a component capable of acting as a set retarder, tended to have a smaller, positive underwater dimensional change compared to the mortar of Comparative Example 2, but none of them simultaneously satisfied the target values ​​for both underwater dimensional change and Shore hardness. On the other hand, the mortars of Examples 1 and 2, which contained a predetermined amount of carbonate (sodium bicarbonate), a component capable of acting as a set retarder, simultaneously satisfied the target values ​​for both underwater dimensional change and Shore hardness due to the moderate retarding effect. These results confirmed that the cement composition of the present invention can form a hardened mortar with excellent underwater dimensional stability and also has excellent rapid hardening properties.

Claims

1. A cement composition comprising a hydraulic component consisting of Portland cement and hemihydrate gypsum, limestone fine aggregate, carbonate, a water-reducing agent, a thickener, and an antifoaming agent, The content of the Portland cement is 20 to 60 mass% and the content of the hemihydrate gypsum is 40 to 80 mass% based on the total amount of the hydraulic components, the content of the limestone fine aggregate is 50 to 250 parts by mass, the content of the carbonate is 0.30 to 1.8 parts by mass, the content of the water-reducing agent is 0.03 to 6.0 parts by mass, the content of the thickener is 0.03 to 4.0 parts by mass, and the content of the antifoaming agent is 0.03 to 4.0 parts by mass, relative to 100 parts by mass of the hydraulic component; Cement compositions.

2. The content of the hydraulic component is 15 to 70 mass% based on the total amount of the cement composition. The cement composition of claim 1.

3. The carbonate is sodium bicarbonate. The cement composition according to claim 1 or 2.

4. The cement composition according to claim 1 or 2 and water are contained. Self-leveling or repair material.

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